• Title/Summary/Keyword: $TCID_{50}$

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Hexon and fiber gene changes in an attenuated fowl adenovirus isolate from Malaysia in embryonated chicken eggs and its infectivity in chickens

  • Sohaimi, Norfitriah M.;Bejo, Mohd H.;Omar, Abdul R.;Ideris, Aini;Isa, Nurulfiza M.
    • Journal of Veterinary Science
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    • v.19 no.6
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    • pp.759-770
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    • 2018
  • Fowl adenovirus (FAdV) is distributed worldwide and causes economic losses in the poultry industry. The objectives of this study were to determine the hexon and fiber gene changes in an attenuated FAdV isolate from Malaysia in specific pathogen-free chicken embryonated eggs (SPF CEE) and its infectivity in commercial broiler chickens. SPF CEE were inoculated with 0.1 mL FAdV inoculum via the chorioallantoic membrane (CAM) for 20 consecutive passages. The isolate at passage 20 (E20), with a virus titer of $10^{8.7}TCID_{50}/mL$ ($TCID_{50}$, 50% tissue culture infective dose), was inoculated (0.5 mL) into one-day-old commercial broiler chicks either via oral or intraperitoneal routes. The study demonstrated that 100% embryonic mortality was recorded from E2 to E20 with a delayed pattern at E17 onwards. The lesions were confined to the liver and CAM. Substitutions of amino acids in the L1 loop of hexon at positions 49 and 66, and in the knob of fiber at positions 318 and 322 were recorded in the E20 isolate. The isolate belongs to serotype 8b and is non-pathogenic to broiler chickens, but it is able to induce a FAdV antibody titer. It appears that molecular changes in the L1 loop of hexon and the knob of fiber are markers for FAdV infectivity.

Potential harmful effects of viral hemorrhagic septicemia virus in mammals

  • Ho, Diem Tho;Kim, Nameun;Yun, Dongbin;Kim, Ki-Hong;Kim, Jae-Ok;Jang, Gwang Il;Kim, Do-Hyung
    • Fisheries and Aquatic Sciences
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    • v.25 no.6
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    • pp.320-326
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    • 2022
  • Most of the emerging diseases that threaten humans are caused by RNA viruses which are extremely mutable during evolution. The fish RNA virus, viral hemorrhagic septicemia virus (VHSV) can infect a broad range of aquatic animal hosts, but the transmissibility of VHSV to mammals has not been thoroughly investigated. Therefore, our study aimed to investigate the potential adverse effects of VHSV in mammals. Briefly, the survival of VHSV was determined using only minimum essential media (MEM-2) and mammalian SNU-1411 and hepa-1c1c7s cells at 15℃ and 37℃. Mice (Mus musculus, 27.3 ± 1.9 g) were intravenously injected with VHSV (2.37E+05 TCID50·mice-1) in triplicate. Clinical signs and survival rates were examined at 14 days post-challenge, and infection was confirmed in the surviving mice. The 50% tissue culture infective dose (TCID50) and polymerase chain reaction analysis were used to determine viral titers and the infection rate, respectively. The titer of VHSV suspended in MEM-2 at 15℃ was reduced by only one log after 8 days, whereas the virus maintained at 37℃ was inactivated 8 days post-inoculation (dpi). There were no recognizable cytopathic effects in either SNU-1411 or hepa-1c1c7s cells inoculated with VHSV at 15℃ and 37℃. VHSV in those cell lines at 37℃ was rapidly decreased and eventually inactivated at 12 dpi, whereas virus at 15℃ remained at low concentrations without replication. In vivo experiment showed that there were no signs of disease, mortality, or infection in VHSV-infected mice. The results of this study indicate that it is highly unlikely that VHSV can infect mammals including humans.

Effect of virus infectivity titer following centrifugation and filtration during virus extraction from fish samples

  • Kim, Wi-Sik;Kim, Jong-Oh;Oh, Myung-Joo
    • Journal of fish pathology
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    • v.28 no.2
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    • pp.113-116
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    • 2015
  • A $0.45-{\mu}m$ membrane filter is generally used to remove bacterial contamination during virus extraction from fish samples. However, the number of fish viruses is drastically reduced after filtration with a $0.45{\mu}m$ filter. In this study, we investigated the effect of filters on virus infectivity titer and the change in virus titer and bacterial number following different centrifugation conditions to determine a suitable procedure for virus extraction from fish samples. $10^{4.05}$ and $10^{5.05}TCID_{50}/ml$ of infectious hematopoietic necrosis virus (IHNV) and $10^{4.05}$ and $10^{4.55}TCID_{50}/ml$ of Oncorhynchus masou virus (OMV) were not detectable after filtration with two types of $0.45-{\mu}m$ filters, except the IHNV titer was reduced by about 10 fold after filter use (company A). No significant difference was found in the virus titer following centrifugation at $880{\times}g$ (30 min) or $3,500{\times}g$ (30 min), whereas IHNV and OMV titers were reduced by about 10 and 10-1000 fold by centrifugation at $14,000{\times}g$ (30 min) and $14,000{\times}g$ (10 and 30 min), respectively. A total of 97.7-99.9% Escherichia coli were eliminated by centrifugation at $880 {\times}g$ (30 min) and $3,500{\times}g$ (30 min). These results show that fish viruses were affected by filtering, even though the effect differed by virus species and filter type. Therefore, centrifugation at $3,500{\times}g$ (30 min) and use of medium with antibiotics may be useful for virus extraction along with a reduction in bacteria.

Studies on Physico-chemical Properties an d Pathogenicity of Porcine Enterovirus Isolated from Feces of Pigherds (돼지 분변 유래 PORCINE ENTEROVIRUS의 물리화학적 특성 및 병원성에 관한 연구)

  • 박정우;이종인;신용호;조우영;최윤식
    • Korean Journal of Veterinary Service
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    • v.14 no.2
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    • pp.110-120
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    • 1991
  • 28 porcine enteroviruses were isolated from 86 pig-feces of 9 swine farms located in south region, Chung-buk, from March to September 1990. Physico-chemical properties and pathogenicity of isolates were investigated. Results obtained throughout experiments are summarized as follows. According to the age, weanlings(40-90 days), sucklings(10-30 days) and adult pigs(6 months over) showed the isolation rate of 67%. 8% and 4%, respectively. By physico-chemical tests, YD-90/22, YD-90/43 and YD-90/64 strains were found to be ether, chloroform and PH stable. Nucleic acid test suggests the virus to have a DNA genome. Most of the Isolates were not evident of hemagglutinin using erythrocytes from various mammalian & avian. 22 strains among the isolates were shown CPE type I and the remainders were CPE type II. 3 strains among isolates of CPE type I strains were neutralized with high titers to serotype 2 antiserum. In the study on virus growth curve in PK-l5 cells, YD-90/22, YD-90/43 and YD-90/64 strains showed the maximum infectivity titers($10^{6.0}-l0^{6.5} TCID({50}ml$) at 4days post inoculation(PI). When 30 day-old commercial piglets were inoculated only intraoral route with the YD-90/22 strain at $10^{6.0} TCID_{50}ml,$ piglets not showed the symptoms. But piglets inoculated by intramuscle route, intraoral and intramuscle route after pretreat with dexamethasone(2.5mg /kg) for 5 days were shown the symptoms of anorexia, diarrhea, pyrexia and ataxia at 4th-6th days PI. The viral reisolation in the virus-inoculated piglets was examined from feces. The viruses were recovered intermittently from 2nd to 16th day PI and at 4th-6th day PI, all piglets excreted viruses.

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Disinfection effect of corona discharged plasma water on fish pathogens (코로나 방전 플라즈마 처리수에 의한 어류 병원체 소독 효과)

  • You, Jin Ho;Lee, Ji Hyun;Mun, Seong Hee;Kwon, Se Ryun;Park, Tae Sup;Kwon, Joon Yeong
    • Journal of fish pathology
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    • v.33 no.1
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    • pp.63-69
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    • 2020
  • Fish culture is constantly threatened by various infectious diseases which are largely transmitted by water. Plasma technology is being used to sterilize polluted water in many industries. In this study, two bacterial pathogens Aeromonas salmonicida and Streptococcus iniae, and a virus (viral hemorrhagic septicemia virus, VHSV) were subjected to plasma water that was produced by a corona discharge system. Growth of A. salmonicida was greatly inhibited from 105.61 CFU/ml in positive control to 103.51 CFU/ml in treated group by only 60 sec contact with plasma water. Similarly, S. iniae was inhibited from 105.85 CFU/ml to 103.40 CFU/ml. VHSV titer also decreased from 104.1 TCID50/ml to 101.45 TCID50/ml by the same treatment. Activation of water by the plasma was confirmed by the existence of ozone in the plasma water. These results suggest that plasma water could efficiently disinfect fish pathogens, possibly by the action of reactive oxygen species contained in the plasma water.

Optimization of Propagation of Anagrapha falcifera Nuclear Polyhedrosis Virus in Spodoptera Frugiperda 21 Cells

  • Lee, Jong-Min;Chang, Kyung-Hwa;Park, Jin-O;Park, Jong-Hwa;Hwang, In-Sook;Lee, Youn-Hyung;Yang, Jai-Myung;Chung, In-Sik
    • Journal of Microbiology and Biotechnology
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    • v.10 no.5
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    • pp.728-732
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    • 2000
  • Propagation of Anagrapha falcifera nuclear polyhedrosis virus(AfNPV) was investigated using well-plates and split-flow air-lift bioreactors. In well-plate experiments, the effects of pH, cell density at a point of infection, serum concentration, DEAE-dextran, and lipid on virus propagation were all closely examined. The AfNPV titer in well-plates was optimal at pH 6.8 and $3{\times}10^6$ cells/$cm^2$. The virus titer was not dramatically affected when the fetal bovine serum concentration was reduced from 10% to 5%. The addition of cholesterol at AfNPV infection of Sf21 cells enhanced the virus titer, whereas the addition of DEAE-dextran did not improve the titer. The AfNPV titer ($3.8{\times}10^7$ $TCID_{50}/ml$) at optimized conditions for well-plate experiments was 2.5-fold higher than for the control. In bioreactor experiments, the AfNPV titer showed its maximum level at air flow rates of 20-40 ml/min. In a split-flow air-lift bioreactor, AfNPV titer ($2.3{\times}10^7\;TCID_{50}/ml$) was 1.5-fold higher than the control when the culture was at pH 6.8 and supplemented with 0.34 mM cholesterol.

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The Screening of Marine Birnavirus (MABV) Infected in Brood Stocks of Flounder, Paralichthys olivaceus (친어용 넙치 성어에 있어 Marine Birnavirus (MABV) 감염에 관한 검색)

  • Oh, Myung-Joo;Jung, Sung-Ju;Kim, Young-Jin;Kim, Hyeung-Rak;Jung, Tae-Sung;Yeo, In-Kyu
    • Journal of fish pathology
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    • v.13 no.1
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    • pp.53-59
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    • 2000
  • Presence of marine birnavirus (MABV) was examined against egg and ovarian fluid, and seminal fluid from the brood stocks of flounder, Paralichthys olivaceus collected from 9 different stations around Korean peninsula. The detection rate of MABV in brood stocks flounder was observed to 34% by PCR. The mean virus titer of the PCR positive fish was $10^{2.30}$ to $10^{4.30}$ $TCID_{50}$/g(ml). By a neutralization test, all of the isolated virus were ascertained to be closely related to marine birnavirus (MABV).

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A Simple Method for the Concentration of Fish Pathogenic Virus in Sea Water (한외여과막을 이용한 해수내 어류 병원바이러스 농축법)

  • Oh, Myung-Joo;Kim, Suk-Ryul;Jung, Sung-Ju;Kim, Hyeung-Rak;Kim, Heung-Yun;Yeo, In-Kyu
    • Journal of fish pathology
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    • v.13 no.1
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    • pp.61-66
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    • 2000
  • A method was developed for concentrating fish pathogenic virus from sea water using membrane ultrafiltration system and centricon. The method consists of passing large volumes (Ca. 20 liter) of sea water through ultrafiltration (PAN) filter followed by cross-flow filtration method and centrifugation use the centricon (Plus-20). This procedure permitted the processing of 20 liter of sea water which resulted in a 20,000-fold reduction in the volume of water and greater than 90% recovery of the seeded MABV.

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Cell adaptation of KPEDV-9 and serological survey on porcine epidemic diarrhea virus(PEDV) infection in Korea (돼지 유행성설사바이러스 국내 분리주(KPED-9) 의 세포증식성 및 혈청학적 역학조사)

  • Kweon, Chang-hee;Kwon, Byung-joon;Kang, Yung-bai;An, Soo-hwan
    • Korean Journal of Veterinary Research
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    • v.34 no.2
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    • pp.321-326
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    • 1994
  • Korean isolate, porcine epidemic diarrhea virus (KPEDV-9) was adapted through serial passages in vero cell. The viral yield reached up to $10^{5-6}$ $TCID_{50}/ml$ at the passage level of 90th. The cell adapted virus was characterized through genetic and morphological examinations. The RNA extracted from virus infected cell revealed the presence of RNA band with molecular size of >20Kb. The electron microscopic examination on purified virus showed the pleomorphic appearance of enveloped particles with 5-10nm surface projections, which fit with the shape of coronavirus. The etiological survey on swine diarrhea by immunofluorescence test(FA) indicated 17.5% positive rate on the PEDV infection. In addition, the incidence were detected both in piglets within two weeks old as well as fattening pigs. Serological survey by ELISA revealed the overall 45% positive result, thus, indicating the PEDV infection are widespread throughout this country.

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Efficacy of live NNV immersion vaccination in three grouper species (Seven band grouper Hyporthodus septemfasciatus, Red spotted grouper Epinephelus akaara, Long tooth grouper Epinephelus bruneus) (바리과 어류 3종(능성어 Hyporthodus septemfasciatus, 붉바리 Epinephelus akaara, 자바리 Epinephelus bruneus)에 대한 신경괴사증바이러스(Nervous Necrosis Virus, NNV)의 생백신 처리 효과)

  • Kim, Si-Woo;Park, Jung-Jun;Hong, Chang-Gi;Oh, Myung-Joo
    • Journal of fish pathology
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    • v.34 no.1
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    • pp.99-104
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    • 2021
  • In this study, we investigated safety and efficacy of a low temperature immunization protocol with NNV in red spotted grouper, Epinephelus akaara and long tooth grouper, Epinephelus bruneus and seven band grouper, Hyporthodus septemfasciatus. Further, growth rate between immunized and naïve fish was evaluated during the experiment to check side effect of immunization. Three grouper species were immunized by immersion method with live NNV at 105.0 TCID50/mL at 16.5℃ for 30 min and reared for 120 days at natural sea water temperature. To evaluate growth rate, total length and wet weight was measured 7 times after immunization. Immunized three grouper species were challenged by intramuscular inoculation with NNV at 104.2 TCID50/100 µL/fish. Immunization at low temperature with live NNV did not show any clinical symptoms of infection, mortality and inhibition of growth. After challenge, cumulative mortality of naïve seven band grouper, red spotted grouper, long tooth grouper were 45, 10, 20 %, respectively. However no mortality was observed at immunized groupers. Thus, it was demonstrated that immunization at low temperature with live NNV are able to protect three different species of groupers without inhibition of growth.